Forum for Science, Industry and Business

Climate change, predators, and the trickle down effects on ecosystems

12.08.2014

Predators play important roles in maintaining diverse and stable ecosystems. Climate change can push species to move in order to stay in their climatic comfort zones, potentially altering where species live and how they interact, which could fundamentally transform current ecosystems.

A symposium focusing on climate's effects on predators—causing cascading effects on whole ecosystems -- will take place on Tuesday, August 12th during the Ecological Society of America's 99th Annual Meeting, held this year in Sacramento, California.

There will be "winners" and "losers" as species adapt to a changing climate. Ecologists are just beginning to understand why different competitors may be favored by climate change and how consumer-resource interactions are modified. Impacts on one species can affect many organisms in an ecosystem.

Because predator species are animals that survive by preying on other organisms, they send ripples throughout the food web, regulating the effects other animals have on that ecosystem. This cause and effect process is called a "trophic cascade," or the progression of direct and indirect effects predators have across lower levels in a food chain.

Sea otter populations provide a historical example of this phenomenon. The fur trade spanning the late 1700s to early 1900s decimated their numbers across their range, from Alaska to Baja California, Mexico. Populations went from an estimated several hundred-thousand to more than a million down to 1,000. Today, there are estimated to be just over 106,000 worldwide, with just under 3,000 in California. Now sea otters and other important predator species face the challenges of a changing climate.

"The near extinction of sea otters is one of the most dramatic examples of human-induced impacts to the structure and functioning of temperate nearshore marine ecosystems," said Rebecca G. Martone, of the Center for Ocean Solutions at Stanford University.

In the U.S., there are two distinct sea otter subspecies, the Northern sea otter (Enhydra lutris kenyoni) and the Southern sea otter (Enhydra lutris nereis). Northern sea otters are found in the Aleutian Islands, Southern Alaska, British Columbia, and Washington. Southern sea otters, also known as California sea otters, live in the waters along the California coastline and range from San Mateo County in the north to Santa Barbara County in the south.

Sea otters live offshore in forests of kelp—huge, yellow-brown, rubbery seaweed reaching from the sea floor to the surface, like tall trees. In coastal North America, sea otters help maintain healthy kelp forests, which benefits other marine species dependent on this habitat.

Sea otters must eat about 25% of their body weight daily to maintain their body temperature since unlike other marine mammals they rely solely on their fur rather than an extra layer of blubber to stay warm—it's like a 120-pound human eating 30 pounds of food per day. Some of otters' favorites are abalone, clams, crabs, mussels, shrimp, and sea urchins. Few predators can crack the globe-shaped spiny urchins, which in unchecked hordes will chew through the holdfasts of the kelp, leaving vast barrens in place of the vibrant forests. The otter is a "keystone predator" whose presence has an outsized effect on its kelp forest habitat.

Without sea otters, the undersea sea urchins they prey on would devour the kelp forests, resulting in dense areas called sea urchin barrens that have lower biodiversity due to the loss of kelp that provide 3-dimensional habitat and a food source for many species. Researchers found that when sea otters arrive in an area from which they have been absent, they begin feasting on urchins. As a result, the kelp forest begins to grow back, changing the structure of kelp forest communities.

Many fish, marine mammals and birds are also found in kelp forest communities, including rockfish, seals, sea lions, whales, gulls, terns, snowy egrets as well as some shore birds. Otters might also offer a defense against climate change because healthy kelp forests can grow rapidly and store large amounts of carbon.

Dr. Martone's analyses of the effects of sea otters on kelp forest ecosystems can help shape predictions of how climate change and trophic cascades, in concert with other drivers, affect coastal ecosystems. The ecological impacts of a changing climate are evident, from terrestrial polar regions to tropical marine environments. Ecologists' research into the tropic cascading effects of predators will assist decision makers by providing important scientific findings to prepare for the impacts of climate change occurring now and into the future. Speakers for the symposia include marine, freshwater and terrestrial experimental ecologists who will present their research and offer insights from different approaches used to studying consumer-resource interactions.

The Ecological Society of America is the world's largest community of professional ecologists and a trusted source of ecological knowledge. ESA is committed to advancing the understanding of life on Earth. The 10,000 member Society publishes five journals, convenes an annual scientific conference, and broadly shares ecological information through policy and media outreach and education initiatives. Visit the ESA website at http://www.esa.org.

Die letzten 5 Focus-News des innovations-reports im Überblick:

Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.

Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...